Device and method in braking systems for motor vehicles

ABSTRACT

Brake systems are disclosed for use in motor vehicles comprising a brake cylinder including a push rod, a brake key for activating a wheel brake on the motor vehicle, a braking lever having a first end for connection to the brake key and a second end for connection to the push rod, and a mount affixed to the push rod between the brake cylinder and the end of the push rod, the mount including a predetermined shape such as a pin and the braking lever including a predetermined shape such as an aperture so that the mount can be coupled to the push rod at a location between the brake cylinder and the end of the push rod by attaching the pin to the aperture. Methods for mounting brake systems in motor vehicles are also disclosed.

FIELD OF THE INVENTION

The present invention relates to a device utilized in braking systemsfor motor vehicles. More particularly, the present invention has itsmain application in connection with braking systems for commercialvehicles. Still more particularly, the present invention relates to amethod for mounting such a braking system on a motor vehicle.

BACKGROUND OF THE INVENTION

Larger motor vehicles, e.g. commercial vehicles, are presently designedwith lower and lower ground clearances. A primary reason for this is theneed to maximize the available cargo space in the vehicle. Since themaximum cargo space is limited by the maximum height allowed and theheight of the vehicle chassis, there is consequently a desire to reducethe height of the chassis in order to thereby increase the cargo space.At the same time, maximum ground clearance is desired in order to avoiddamage to the vehicle when driving over rough ground. The demands of lowheight of the chassis and large ground clearance in turn set limitationswhen designing the braking system of the commercial vehicle. This isparticularly true in the case where the braking system comprises acompressed-air driven brake cylinder, which may be mounted standing in agiven position in relation to a wheel shaft, and when the brake cylindercomprises a substantially vertically projecting push rod. With such aconstruction, the height of the chassis of the vehicle is limited by thelength of the push rod.

It is known in the prior art that the end of the push rod, whichprotrudes from the brake cylinder, is normally threaded and connected toa brake key by means of a special lever member.

When the braking system is activated by the driver of the vehicle, thepush rod is pressed out from the brake cylinder, thereby influencing thebrake key by means of the lever. The brake key, in turn, activates thewheel brake.

With reference to FIG. 1, a previously known system of theabove-mentioned kind will be described. FIG. 1 shows a brake cylinder 1,intended to be mounted on a wheel shaft in a commercial vehicle. Thebrake cylinder 1 comprises a push rod 2, which is pressed outessentially in a vertical direction (i.e., downwards in the drawing)when the braking system is activated by the driver of the vehicle. Themovement of the push rod 2 is transferred to a brake key 3 by means of abraking lever 4. The brake key 3 is arranged substantially parallel tothe wheel shaft which is to be braked.

When mounting this previously known device, i.e. when the braking lever4 is to be mounted in order to join the push rod 2 to the brake key 3,the brake cylinder 1 and the brake key 3 have to be pre-installed, i.e.they are placed in the vehicle in advance. In this way, installation ofthe lever 4 may be accomplished by mounting one end of lever 4,comprising an aperture 5 with internal splines, onto outer splines 6 onthe brake key 3. The spline separation which is utilized in this splinecoupling will cause the opposite end of the lever 4 to be positionedadjacent to the push rod 2 in a position which may vary within a certaininterval in relation to the end of the push rod 4. The exact positionfor the end of the lever 4 is determined by the fixed spline separationand the length of the lever 4. The splined coupling 5, 6 is thereafterlocked by means of a locking screw 7 with appurtenant nut 8.

The next step in the mounting operation is that a link element,consisting of two link members 9 and 10, respectively, is broughttogether on both sides of the push rod 2 and the end of the lever 4,which has been placed adjacent to the push rod 2. The first link member9 is joined to the second link member 10 by means of two screws, 11 and12, which are inserted into corresponding holes, 13 and 14, in thesecond link member 10, while a pin 15 in the first link member 9 ispassed through a hole 16 in the lever 4 and into a further hole 17 inthe second link member 10. Thereafter, the link element 9, 10 is screwedon by means of the screws, 11 and 12, and nuts, 18 and 19. The linkmembers, 9 and 10, further comprise internal threads 20 (which are onlyevident from the link member 10 in FIG. 1) which interact with threads21 on the push rod 2. In this way, the push rod 2 may be locked to thelink elements 9, 10 and transfer its movement to the brake key 3 bymeans of the lever 4.

As mentioned above, the spline separation of the splined coupling 5, 6implies that the end portion of the lever 4 facing towards the push rod2 will be positioned in a position which may vary vertically within acertain interval. This interval is normally of the magnitude of approx.30 mm. Thus, the length of the link element 9, 10 cannot be below thisinterval, since it has to be utilized for bridging the distance betweenthe push rod 2 and the lever 4. The fact that the interval must beaccomodated by the link element 9, 10, in its turn, means that this hasto project downwards a relatively long distance below the push rod 2.This constitutes a disadvantage, since it creates an essentiallimitation when the ground clearance and the height of the chassis ofthe vehicles are concerned.

SUMMARY OF THE INVENTION

A main object of the present invention is to achieve an improved devicefor joining a push rod and a brake key in a braking system, particularlyfor commercial vehicles, which braking system utilizes a compressed-airdriven brake cylinder with a vertically projecting push rod. Inparticular, it is an object of the present invention to createconditions for optimizing the relation between the ground clearance andthe height of the chassis of the vehicle.

A further object of the invention is to provide a simplified mounting ofa braking system for a commercial vehicle, having a minimum number ofcomponents and working steps in the mounting operation.

In accordance with the present invention, these and other objects havenow been realized by the invention of brake system for use in motorvehicles comprising a brake cylinder including a push rod having an endportion projecting from the brake cylinder upon activation of the brakecylinder, a brake key for activating a wheel brake on the motor vehicle,a braking lever including a first end and a second end, the first end ofthe braking lever adapted for connection to the brake key and the secondend of the braking lever adapted for connection to the push rod, and amounting member affixed to the push rod at a location between the brakecylinder and the end of the push rod, the mounting member including afirst attachment member and the braking lever including a secondattachment member whereby the braking lever can be coupled to the pushrod at a location between the brake cylinder and the end of the push rodby attaching the first and second attachment members to each other. Inaccordance with one embodiment of the brake system of the presentinvention, the first attachment member comprises a predetermined shapeof the mounting member and the second attachment member comprises apredetermined complementary shape of the braking lever. In a preferredembodiment, the predetermined shape of the mounting member comprises apin and the predetermined complementary shape of the braking levercomprises an aperture.

In accordance with one embodiment of the brake system of the presentinvention, the push rod includes external threads and the mountingmember comprises a substantially sleeve-shaped member including internalthreads adapted to mate with the external threads of the push rod.

In accordance with another embodiment of the brake system of the presentinvention, the system includes a support including a first end and asecond end, the first end of the support adapted for connection to themounting member and the second end of the support adapted for connectionto the braking lever. In a preferred embodiment, the mounting memberincludes a third attachment member and the first end of the supportincludes a fourth attachment member. More preferably, the thirdattachment member comprises a predetermined shape of the mounting memberand the fourth attachment member comprises a predetermined complementaryshape of the support. Most preferably, the predetermined shape of themounting member comprises a pin and the predetermined complementaryshape of the support comprises an aperture.

In accordance with another embodiment of the brake system of the presentinvention, the first end of the braking lever is adapted for connectionto the brake key by means of a splined coupling.

In accordance with the method of the present invention, a method hasbeen developed for mounting a brake system in a motor vehicle, the brakesystem comprising a brake cylinder including a push rod having an endportion projecting from the brake cylinder upon activation of the brakecylinder and a brake key for activating a wheel brake on the motorvehicle, the method comprising mounting a mounting member on the pushrod at a location between the brake cylinder and the end of the pushrod, providing a braking lever having a first end and a second end,connecting the second end of the braking lever to the mounting member atthe location between the brake cylinder and the end of the push rod, andconnecting the second end of the braking lever to the brake key in adirection substantially parallel to the longitudinal direction of thebrake key. In a preferred embodiment, the mounting member includes afirst attachment member having a predetermined shape integral therewithand the second end of the braking lever includes a second attachmentmember having a predetermined complementary shape integral therewith,the method further comprising connecting the second end of the brakinglever to the mounting member by guiding the predetermined shape of themounting member into the predetermined complementary shape of the secondend of the braking lever.

In accordance with one embodiment of the method of the presentinvention, the method includes separately connecting the mounting memberto the braking lever by means of a separate support.

The present invention is based on a mounting device which, together withthe braking lever, comprises means for coupling the push rod to thebraking lever, by means of the mounting device, at a point which issituated within the end of the push rod which projects from the brakecylinder. In this way, the only limitation for the height of thechassis/ground clearance is given by the length of the push rod, i.e.the distance between the brake cylinder and the lever may be madeshorter than in previously known devices.

According to a preferred embodiment of the present invention, the pushrod may be coupled to the lever by means of the mounting device sincethe mounting device comprises a modification of shape, preferably in theform of a pin, which interacts with a corresponding modification ofshape, preferably a hole, which has been provided in the braking lever.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed description, the invention will be describedin greater detail with reference to the attached drawings, in which

FIG. 1 is a front, exploded, perspective view of a known device in abraking system;

FIG. 2 is a front, perspective view of a device in a braking systemaccording to the present invention;

FIG. 3 is a side, perspective view of a rear axle in which the presentinvention may be utilized;

FIG. 4a is a top, elevational view showing the relationship between thepush rod and the brake key prior to mounting the device according to thepresent invention;

FIG. 4b is a side, elevational view of the braking lever during mountingthe device according to the present invention; and

FIG. 4c is a side, elevational view of the device according to thepresent invention after mounting.

DETAILED DESCRIPTION

Referring to the drawings, FIG. 2 is a perspective view of a device inaccordance with the present invention which, according to a preferredembodiment, is utilized in connection with a braking system for acommercial vehicle. The drawing shows the device in its mounted state.The braking system comprises a compressed-air driven brake cylinder 22,of a previously known type, which may be influenced by the driver of thevehicle when braking. The brake cylinder 22 comprises a push rod 23, thelower end of which is provided with external threads 24. According tothis embodiment, the brake cylinder 22 is mounted standing up by meansof an attachment bracket 25, which is firmly affixed to the vehicle. Thebrake cylinder 22 may be mounted with an extension substantially in thevertical direction, or with another orientation.

The push rod 23 is known to be arranged to be pushed out from the brakecylinder 22 when the braking system is activated. In this manner, themovements of the push rod 23 are transferred to a brake key 26 by meansof a braking lever 27. The brake key 26, in turn, is connected to a (notshown) wheel brake. The brake key 26 is preferably oriented with anextension which runs along an axis 28 which is substantially parallel tothe wheel shaft of the vehicle, which supports the wheel which is to bebraked.

The lever 27 and the brake key 26 may be connected by means of a splinedcoupling 29, which is formed by external splines 30 on the brake key 26,and internal splines 31 arranged in a hole 32 at one end of the lever27. The hole 32 is slotted, whereby the splined coupling 29 may beclamped by means of a locking screw 33, interacting with a (not shown)nut on the underside of the right end portion of the lever 27.

When mounting the device, it is required that the brake cylinder 22 andthe appurtenant push rod 23 have been pre-mounted and are in position.Furthermore, the brake key 26 is pre-mounted. For this reason, the lever27 must be brought into position in the direction which is marked withan arrow 34 in FIG. 2, i.e. in a direction which is essentially parallelto the axis 28. Before the lever 27 is brought into position, however,in accordance with the present invention, a special mounting device, inthe form of a cross 35, is mounted on the push rod 23. As will becomeevident by the discussion below, the cross 35 is composed of asleeve-shaped element which is provided with internal threads,interacting with the threads 24 on the push rod 23. Furthermore, thecross 35 comprises an intermediate portion 36, having a square(optionally rectangular) cross-section and which is provided with twopins, out of which a first pin is intended to project through a hole inthe lever 27 (not evident from FIG. 2), and a second pin 37 is intendedto project through a hole 38 which has been tooled into a separatesupporting member 39. This supporting member 39 may, in turn, be mountedto the lever 27 by tightening two screws 40 which interact withcorresponding holes in the lever 27.

In FIG. 3, a rear axle 41 for a commercial vehicle is shown, for whichthe invention has its main application. The location of the brakecylinder 22 on the bracket 25 is evident from the drawing. The brakecylinder 22 is arranged such that the push rod 23, when activated, canproject a certain distance from the brake cylinder 22. Furthermore, thepush rod 23 is connected to the braking lever 27 by means of thesupporting member 39. The brake key 26 runs inside a brake key cover 42comprising an opening which emerges where the braking device of the rearaxle 41 (not shown) is arranged, i.e. in connection to a wheel shaft 43.

In FIGS. 4a-4 c, the procedure for mounting the device in accordancewith the present invention is illustrated. FIG. 4a shows the initialposition, whereby the push rod 23 is shown in cross section, and thebrake key 26 is arranged in a certain predetermined position in relationto the push rod 23. Firstly, the cross 35 is screwed upwards a certaindistance on the push rod 23. It can therefore be seen that the pins, 37and 44, on the intermediate section 36 of the cross 35 are directedsubstantially parallel to the brake key 26. As is evident from FIG. 4b,the braking lever 27 is thereafter mounted substantially parallel to thedirection in which the brake key 26 has its extension. The mountingdirection is indicated by the arrow 34. When mounting, it is ensuredthat the hole 32 in one end of the lever 27 is brought inwards over thebrake key 26 so that the external splines 30, which are located on thebrake key 26, come into contact with the internal splines 31 located inthe hole 32. Furthermore, it is ensured that the pin 44 is aligned withthe pin hole 45 in the lever 27. If a fine adjustment of the position ofthe cross 35 along the push rod 22 is necessary, this is achieved byscrewing the cross 35 a number of turns upwards or downwards.

The lever 27 is curved in such a way that it comprises an intermediateportion 46, the extension of which is mainly parallel to the brake key26. In this way it is possible for the location of the pin hole 45 to beslightly displaced in the direction along the length thereof in relationto the hole 32 in the opposite end of the lever 27. This, in turn,implies that the lever 27, may be brought a small distance over thebrake key 26, while the cross 35 still may be turned in order to befinely adjusted. This facilitates mounting of the lever 27.

The construction of the above-mentioned supporting member 39, comprisinga planar support surface 47 for contacting the intermediate portion 46of the lever 27, is also evident from FIG. 4b. As mentioned above, thesupporting member 39 additionally comprises a pin hole 38 arranged tointeract with the pin 37. Furthermore, the supporting member 39comprises two holes 48 (of which only one is evident from FIG. 4b),intended for the through screws 40, which are screwed into thecorresponding holes in the lever 27. In FIG. 4c, the device is shown inits mounted state, whereby the cross 35 has been adjusted into thecorrect position and its pins 37 and 44 have been fitted into the lever27 and the supporting member 39, respectively. When the lever 27 is thenpushed completely into position on the brake key 26, the splinedcoupling 29 is locked by means of tightening the fastening screw 33.Finally, the supporting member 39 is locked by means of the screws 40.

By means of the present invention, it is ensured that the end portion ofthe lever 27, facing the push rod 23, is positioned so that it isconnected to the cross 35 at a point which lies within the end of thepush rod 23 which projects from the brake cylinder. In the case wherethe brake cylinder is mounted vertically, this accordingly implies thatthis point is situated above the lower end of the push rod 23 (cf. FIG.2). This means that no unnecessary extension of the push rod 23 isrequired. Instead, it is the maximum length of the push rod 23 whichsets the limit to the height of the chassis and the ground clearance ofthe vehicle.

The present invention is not limited to the above-mentioned embodiment,but may be varied within the scope of the subsequent claims. Theintermediate portion 46 of the lever 27 may, for instance, be adapted inlength according to an existing mutual distance between the push rod 23and the brake key 26. Furthermore, the cross 35 may be provided withsmall holes which interact with pins in the lever and the supportingmember, instead of the reverse thereof.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

What is claimed is:
 1. A brake system for use in motor vehiclescomprising a brake cylinder including a push rod projecting from saidbrake cylinder, said push rod having a lower end movable away from saidbrake cylinder upon activation of said brake cylinder, a brake key foractivating a wheel brake on said motor vehicle, a braking leverincluding a first end and a second end, said first end of said brakinglever adapted for connection to said brake key and said second end ofsaid braking lever adapted for connection to said push rod, and amounting member affixed to said push rod at a location above the lowerend of said push rod so that the lower end of said push rod extendsbelow said mounting member, said mounting member including a firstattachment member and said braking lever including a second attachmentmember whereby said braking lever can be coupled to said push rod at alocation between said brake cylinder and said lower end of said push rodby attaching said first and second attachment members to each other. 2.The brake system of claim 1 wherein said first attachment membercomprises a predetermined shape of said mounting member and said secondattachment member comprises a predetermined complementary shape of saidbraking lever.
 3. The brake system of claim 2 wherein said predeterminedshape of said mounting member comprises a pin and said predeterminedcomplementary shape of said braking lever comprises an aperture.
 4. Thebrake system of claim 1 wherein said push rod includes external threadsand said mounting member comprises a substantially sleeve-shaped memberincluding internal threads adapted to mate with said external threads ofsaid push rod.
 5. The brake system of claim 1 including a supportincluding a first end and a second end, said first end of said supportadapted for connection to said mounting member and said second end ofsaid support adapted for connection to said braking lever.
 6. The brakesystem of claim 5 wherein said mounting member includes a thirdattachment member and said first end of said support includes a fourthattachment member.
 7. The brake system of claim 6 wherein said thirdattachment member comprises a predetermined shape of said mountingmember and said fourth attachment member comprises a predeterminedcomplementary shape of said support.
 8. The brake system of claim 7wherein said predetermined shape of said mounting member comprises a pinand said predetermined complementary shape of said support comprises anaperture.
 9. The brake system of claim 1 wherein said first end of saidbraking lever is adapted for connection to said brake key by means of asplined coupling.
 10. A method for mounting a brake system in a motorvehicle, said brake system comprising a brake cylinder including a pushrod projecting from said brake cylinder, said push rod having a lowerend movable away from said brake cylinder upon activation of said brakecylinder and a brake key for activating a wheel brake on said motorvehicle, said method comprising mounting a mounting member on said pushrod at a location above said lower end of said push rod so that thelower end of said push rod extends below said mounting member, providinga braking lever having a first end and a second end, connecting saidsecond end of said braking lever to said mounting member at saidlocation above said lower end of said push rod, and connecting saidsecond end of said braking lever to said brake key in a directionsubstantially parallel to the longitudinal direction of said brake key.11. The method of claim 10 wherein said mounting member includes a firstattachment member having a predetermined shape integral therewith andsaid second end of said braking lever includes a second attachmentmember having a predetermined complementary shape integral therewith,said method further comprising connecting said second end of saidbraking lever to said mounting member by guiding said predeterminedshape of said mounting member into said predetermined complementaryshape of said second end of said braking lever.
 12. The method of claim10 including separately connecting said mounting member to said brakinglever by means of a separate support.
 13. A method of mounting a brakesystem in a motor vehicle having a premounted rod, cylinder and brakekey mounted to the vehicle, the brake key having an end to be coupled tothe rod, comprising: a) attaching a mounting member to the rod at alocation above a lower end of the rod so that said mounting member islocated between the lower end of the rod and the cylinder and so thatthe lower end of said push rod extends below said mounting member, themounting member having a first attachment member; b) providing a leverhaving a first end for attachment to the end of the brake key and asecond end having a second attachment member; c) bringing into positionthe lever toward the end of the brake key, after the mounting member isattached to the rod, so that the first attachment member is attached tothe second attachment member and the first end of the lever is attachedto the end of the brake key; d) attaching a supporting member to thelever and the mounting member.
 14. The method of claim 13, wherein themounting member has a first side and a second side opposite the firstside, the second attachment member is attached to the first attachmentmember at the first side, and the supporting member is attached to themounting member at the second side.
 15. The method of claim 13, whereinthe lever is curved and has an intermediate portion so that the firstend of the lever is offset in relation to the second end of the lever.16. The method of claim 15, wherein the lever is brought into positionso that the first end of the lever is attached to the brake key beforethe first attachment member is attached to the second attachment member.